The Curiosity Mars rover has started drilling in a clay-bearing unit on the slopes of Mount Sharp, a high-priority target. Image: NASA/JPL-Caltech/MSSSNASA’s Curiosity Mars rover has finally started drilling into a clay-bearing unit on the lower slopes of Mount Sharp, collecting samples that formed in the presence of water. Reaching this area has been a major objective ever since Curiosity landed in Gale Crater seven years ago.Back on Earth, meanwhile, engineers in Germany and the United States are carrying out additional tests to figure out what’s preventing a hammer-like device known as “the mole” from pounding into the martian soil near the InSight Mars lander, pulling a string of sensitive temperature sensors along behind it.Launched in May 2018, InSight – the acronym stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport – landed on Mars last 26 November. It was equipped with just two major instruments: an ultra-sensitive seismometer provided by the French space agency and the German Heat Flow and Physical Properties Probe, or HP3.The HP3 instrument was designed to use a spring-driven internal hammer-like device – the mole – to pound its way down into the martian soil trailing a cable carrying ...